This entire project is based on the hypothesis that we can design and develop new synthetic triterpenoids that would eventually be clinically useful for chemoprevention and treatment of cancer. The project is articulated in 6 Specific Aims that cover the entire range of preclinical studies, all the way from design of new drugs, elucidation of their biological activity and molecular mechanism of action, study of their pharmacokinetics, and finally, testing of efficacy for prevention of cancer in animal models of carcinogenesis that are considered relevant to actual human disease. Our Specific Aims are as follows: (1) To continue to synthesize new triterpenoids, with our priorities determined by results obtained in the in vitro and in vivo test systems described in the subsequent Specific Aims. These studies will be done in collaboration with the Department of Chemistry at Dartmouth College. (2) To continue to test the new triterpenoids from Specific Aim 1 for their biological activity on a series of cell culture assays that are relevant to chemoprevention of cancer. Such assays will measure anti-proliferative and apoptotic activity, induction of differentiation in tumor cells, and anti-inflammatory activity. (3) To evaluate the molecular mechanism of action, in cell biology and molecular biology assays, of the new triterpenoids from Specific Aim 1. In conjunction with these studies, we will attempt to identify the proximate molecular target(s) that mediates the anti-proliferative, apoptotic, anti-inflammatory, and differentiating actions of the synthetic triterpenoids made at Dartmouth. (4) To evaluate the ability of new triterpenoids to induce apoptosis in cells that are relevant to human carcinogenesis, with special emphasis on induction of apoptosis in immortalized human breast epithelium, both non-neoplastic and neoplastic. (5) To evaluate the pharmacokinetics of promising new triterpenoids, in preclinical studies, to optimize choice of agents that might eventually be used for preventing cancer in men and women. As an adjunct to the pharmacokinetics, we will also undertake some preliminary assays of short-term toxicity in rats and mice. (6) To test promising new triterpenoids in appropriate animal models for chemoprevention of cancer, with special emphasis on prevention of breast and colon cancer. Triterpenoids previously synthesized with support from this grant are already under consideration for clinical use in treatment of leukemia. Historically, many chemopreventive agents have entered clinical use for cancer prevention by first being shown to be active in treatment protocols, and we intend to continue to pursue this cross-talk between therapeutic and preventive approaches to the cancer problem with the results of the proposed new studies.